Popular passages

Page 7 - Congress as required by law, copy of the report of the commanding officer of Watertown Arsenal, of "Tests of iron and steel and other material for industrial purposes," made at that arsenal during the fiscal year ended June 30, 1906.

Page 146 - Beilby4 and his conclusions have been confirmed and accepted by many other investigators. According to him, a surface skin may be built up by mechanical movement which gives unmistakable evidence that the surface must have passed through a state in which it possessed the perfect mobility of a liquid. This surface possesses distinctive properties which differentiate it from the surface beneath it. Hardening thus results from the formation at all the internal surfaces of slip or shear of mobile layers...

Page 138 - The depth of heat crack varies irregularly in each section, and somewhat regularly in sections proceeding from A to E, increasing in depth toward the powder chamber. The number of cracks does not, however, vary in the same way. In section E, where the greatest erosion has taken place, the smallest number of cracks appear.

Page 138 - Sections B, C, D and E show a hard layer of metal on the face cut normal to the axis. All five sections show the hard layer on the face cut parallel to and along the driving edge. The depth of the layer of hard metal on the face normal to the axis varies as follows: A, 0.0000 in.; B, 0.0004 in.; C, 0.0008 in.; D, 0.0013 in.; E, 0.0015 in. The cracks are undoubtedly due to the unequal expansion...

Page 146 - In wiredrawing it becomes necessary to frequently anneal the metal in order to restore the plasticity, and thus prevent it from cracking or breaking. This phenomenon is common not only to the ductile metals, but is also a property of the more brittle metals, such as antimony, and of minerals, such as crystallized calcite, etc. The mechanism of this action has been studied in detail by Beilby, and an interesting résumé of his work will be found in his presidential lecture on "The nard and soft states...

Page 145 - ... produce a rapid loss of heat. Mechanical Deformation or Cold Work. — It is a well-known fact that when any ductile metal is subjected to mechanical deformation it becomes hard and brittle, and if the work is carried too far, cracking will result. Even the most ductile metals, such as gold and platinum, lose their plasticity and become hard and brittle when subjected to drawing, hammering, etc. In wire drawing it becomes necessary to anneal the metal frequently in order to restore plasticity...